Method of and apparatus for insulating electrical conductors



A. H. ADAMS 1,765,520

METHOD OF AND APPARATUS FOR INSULATING ELECTRICAL CONDUCTORS June 24, 1930.

Filed July 25, 1925 /n vehfar Arf/Iu/ A. Adams mm: A

Patented June 24, .1930

UNITED STATES PATENT OFFICE ARTHUR HERMAN ADAMS, OF LA GRANGE, ILLINOIS, ASSIGNOR T WESTERN ELECTRIC comm, 'moonromjrnn, or NEW YORK, N. Y., A CORPORATION OF NEW YORK METHOD 0] .AND APPAEATUS FOB INSULATING ELECTRICAL GONDUCTOBS Application filed. m 25,

electricalconductors with a bakedinsulatm ing coating.

In order to attain this object in accordance with the features of the invention in one embodiment thereof, a wire continuously passes through a supply of insulating compound, becoming coated therewith, and

thence over two spaced metal rollers connectedfwith a source of electrical current so that a current of high frequency passes through the length of the wire between the rollers, the applied coating between each roller and the wire functioning as a die1ectrio of a condenser. The heating of the everchanging lengths of portions of the wire by the current passing therethrough bakes the 5 s coating from the interior thereof outwardly.

In a modified form the rollers are replaced by pairs of suitably spaced condensers between which the coated wire passes.

The method may be practiced by employing an'apparatus embodying the invention or baking enamel insulation on the wire in the manner hereinafter described and shown on the accompanying drawings, wherein Fig. l'isla diagrammatic view in sectional elevation of the preferred form of the I apparatus for bakinginsulation on the wire;

Fig. 2 is a similar view of a modified form of the apparatus shown in Fig. -1, and

Fig. 3 is a diagrammatic View of the electrical circuit employed with either form of apparatus.

It is believed that the details of the method will be fully understood from a descrr tion of the apparatus by which it may practiced. Fi 1 of the drawing illustrates the preferred orm of apparatus, which comprises an insulating compoundcontainer 10 which has therein a quantity of insulating compound -11,' preferably in liquid form of any suitable character which may be baked 1925. Serial No. 46,052.

metal for the purpose of retaining and holda ing the heat during the process of baking the insulating coating upon the wire. In determining the proper len th of this tube the factors which must be ta en into consideration are the size of the wire to be insulated and the speed at which the wire travels through this chamber. the tube or heat retaining chamber 12 is purposely tapered inwardly as shown at 13 for the purpose of retarding the escape of heat, butat the same time providing an opening of suficient size at the upper end thereof to permit the vapor resulting from the baking of the insulatlng compound on the wire to escape. Mounted within the compound container 10 on suitable bearings and in a position to be partially submerged in the insulating compound 11 is a sheave 14. This sheave is provided with a suitable collar 15 formed integrally therewith for a purpose hereinafter set forth. Mounted in any suitable position adjacent the heating chamber on a suitable spindle is a wire supply spool or reel 16 from which a wire 17 1s fed over a supply guide roller 18. The guiding pulley or supply guide roller 18 is positioned vertically over the sheave 14 so as to direct the wire in a Vertical line downwardly. Positioned below the supply guide roller 18 and at one side thereof and mounted on a sui t able bearing is a soft iron idler pulley 19 for the urpose hereinafter set forth. The wire 17 is led from the supply spool or reel The upper end of downwardly aroun the sheave l4: and u ,wardly in a vertical direction through t e longitudinal center of the heat retaining tube or chamber 12 where it is trained around an coate upper sheave 20 and thence vertically in a downward direction around the soft iron shown at 14 and may again receive a second coat of insulating compound and pass through a second heat retaining chamber upwardl over a pulley or sheave similar to that s own at 20, from where it may again be repeated and several coats of insulating compound thus applied according to the requirements, after which it is led to a receiving reel or spool 21, which may be operativel driven in any well known manner to win the insulated wire thereon.

. One of the important features of the present process of and apparatus for baking insulation on the wire consists of passing an electrical current successively through portions of a continuously movin wire and thereby heating the wire overfiiis portion in such a manner that the insulation is baked thereon during the time it is traveling through the heat retaining chamber.

Another important feature is that the solvents and distillable portions of the compound or enamel or varnish are driven off from the inside of the coating outwardly, and the outer surface of the coating remains fluid longer than the inner portion. This obviates the microscopic pores that might sometimes occur when the heating is done" from the outside inward, by reason of the outer surface partially drying first and being ruptured by vapors evolved from the inner portion of the compound layer.

The a paratus for accomplishing or causing the e ectrical current to pass through this ever-changing portion or length of the wire comprises an oscillator or other source of high frequency current of relatively low voltage as shown diagrammatically at 22, which is connected by suitable wiring 23 and a spring pressed contact member 24 with a collar 25 formed integrally with the upper sheave or pulley 20. The other terminal is connected by a wire 26 and springcontact member 27 which contacts with the collar 15 of the sheave or pulley 14. It will, of course, be understood that the coating of insulation between the rollers and the wire forms the dielectric of a condenser at both the upper and lower ends of the length of wire passing from the sheave 14 to the sheave 20, and in order to revent the returning portion of the coated the portion being baked within the heat retaimng chamber or tube 12 a high retardawire from short circuiting tion impedance to the high frequency alternating current is introduced in this returning coated portion by passin the returning portion several times aroun the soft iron idler 19, as previously described. The circuit thus established is shown diagrammatically in Fig. 3.

It should be understood that the frequency used should be so high that the im edance of the two condensers, formed by t e wire passing over the sheaves 20 and 14, will be negligible in relation to the resistance of that portion of the wire it is desired to heat. This is necessary both because these condensers are quite variable and because otherwise the circuit would be very inefiicient, in that energy would be dissipated elsewhere than where desired.

From the above description it will be seen that as the movin wire is led from the supply spool into t e insulating compound 11, where it is coated with the same, the ever-changing portions of equal length successively extending between the sheaves 14 and 20 are being heated by the hi h fre-. quency electrical current passing t rough this portion as part of the circuit, and that i the heat retaining chamber or tube 12 retains the heat in a manner to insure complete bak- I ing or hardening of the insulation covering.

In the modified form shown in Fig. 2 the manner in which the wire is led from the supply reel 16 to the receiving reel 21 is su stantially identical with that shown in Fig. 1, the only difference being that adjacent the upper and lower ends of the heat retaining "chamber or tube 12 are positioned two electrodes or condenser plates 28 and 29 which are operatively associated with the coated wire for conveymg electrical current to that portion of the coated wire extending between these plates. The coated wire is guided at the upper end of the heat retaining chamber or tube 12 by a glass or nickel roller 30. The roller 30 maintains the wire in a m relatively fixed vertical line during its moyement through the heat, retaining chamber. The statements given above in connection with the description ofthe apparatus shown in Fig. 1 regarding the circuit, the char- 5 actor of the current employed, and the introduction of impedance to tprevent short circuiting of one portion 0 the wire b another portion thereof are eilually applicable to the apparatus shownin itg. 2.

While in the above speci cation I have described specific embodiment which my invention may assume in practice, it wi l, of course, be understood that various further modifications may be made without departing from the spirit and scope of the invention as expressed in the following claims.

\Vhat is claimed is:

1. In an apparatus for insulating an electrical conductor, means for applying a coating of insulating material to the conductor,

' a source of high frequency electrical curadjacent the coated conductor for rent, spaced terminals therefor positioned assing high frequency electrical current t rough and thereby heating the portion of the conductor between the terminals to bake the coating thereon, and means to cause a relative movement between the terminals and the conductor to continuously change the' portion of the conductor bein heated to- .thereby continuously bake t e coatingthereon.

2. The method of baking a coatingon an electrical conductor, which consists in generating a high frequency electrical currentoutside of said wire, passing said current through the coating and through a selected portion of the conductor and thereby heating the portion to bake the coating.

3. The method of baking a coating on an electrical conductor, which consists in positioning adjacent the conductor at spaced points, terminals of a source of high frequency electrical current to cause an electrical current to pass through the portions of the conductor between the points, thereby heating the portions to bake the coating.

4. The method of bakin a coating on an electrical conductor, which consists in employing the coating as a dielectric in a condenser for passing a high frequency current through the conductor, and thereby heating the conductor to bake the coating.

5'. The method of baking a coating ap-, plied to an electrical conductor, which con? sists in moving the conductor along a predetermined path, and simultaneously passing electrical heating current through adjacent ever-changing equal lengths of the for passing a high frequency electrical heating current through the coated conductor.

8. In an apparatus for baking a coating applied to a base, means for moving the coated base along a predetermined path, and means employing the coating as a dielectric in a condenser for passing a high frequency electrical heating current through the base durin such movement.

9. 1%1 an apparatus for baking a coating applied to a base, means for moving the coated base along a predetermined path, and means employing the coating as a dielectric in a condenser for passing a high frequency electrical heating current through everchanging equal lengths of the base during such movement.

10. In an apparatus for baking a coating applied to a base, means including spaced guide members for movin the coated base alon a predetermined pat means employing the guide members as terminals and employing the applied coating as a dielectric in a condenser for passing a high frequency electrical heating current through everchanging equal lengths of the base during such movement, and means for substantially confining thev heating current to said everchanging lengths.

11. In an apparatus for baking a coating applied to a base, spaced guide members positioned adjacent the coated base, means or causing a relative movement between the coated base and the guide members, and means employing the guide members as ter- 'minals and employing the applied coating as a dielectric in a condenser for passing a high frequency electrical heating current through ever-changing equal lengths of the base during such movement. I

In witness whereof, I hereunto subscribe my name this 14th day of July, A. D. 1925.

' ARTHUR HERMAN ADAMS. 

